Asymmetric nitrogen. 76. Quantum chemical study of geometry and configurational stability of ketenimines

MNDO calculations were carried out of the ground and transitional states of the planar inversion of the N atom for ketenimines containing σ (Me, NH2, OH, OMe, and F) and π (CH = O) acceptor N substituents as well as for C-amino- and C-formylketenimines. Configurationally stable N-amino-, N-alkoxy-, and N-fluoroketenimines (inversion barriers ∼27–45 kcal/mole) are of interest for further experimental stereochemical studies. The geometry of the ketenimine fragment is determined in general bynN-πCC* conjugation. Other orbital and Coulombic interactions affect C- and N-substituent orientation relative to this fragment.